The subject matter of the present invention relates to a method and apparatus for comparing, via a cross-correlation technique, a first data set having known geologic features with a second data set having unknown geologic features thereby generating an output record, known as a xe2x80x98correlation spectral volumexe2x80x99, which records and displays the degree to which the unknown geologic features of the second data set substantially match one or more of the known geologic features of the first data set.
When a seismic operation is performed on a particular portion of an Earth formation, a resultant set of seismic data is generated. The seismic data must be analyzed to determine a set of geologic characteristics of the particular portion of the Earth formation. A first analysis method which may be used to perform this analysis of the resultant set of seismic data involves the use of the Fast Fourier Transform. A second analysis method which may be used to perform the aforementioned analysis involves the use of the so-called Chebyshev Decomposition. However, neither the Fast Fourier Transform nor the Chebyshev Decomposition include a mechanism for using any suitable set of standard comparison traces (which are not necessarily a part of an input seismic volume) having known geologic characteristics for comparison against a set of other traces having unknown geologic characteristics to thereby produce an output record that records the differences, in geologic characteristics, between each of the xe2x80x98known geologic characteristicxe2x80x99 standard comparison traces and each of the xe2x80x98unknown geologic characteristicxe2x80x99 other traces.
Therefore, a third analysis method is needed for performing the analysis of the resultant set of seismic data for the purpose of determining the set of geologic characteristics of the particular portion of the Earth formation. That third analysis method is summarized below and is set forth in detail in the xe2x80x98Description of the Inventionxe2x80x99 section of this specification.
Accordingly, a third analysis method is disclosed for performing an analysis of a resultant set of seismic data, generated in response to a seismic operation performed on a particular portion of an Earth formation, for the purpose of determining a set of geologic characteristics of the particular portion of the Earth formation. When the third analysis method is performed, a cross-correlation technique is utilized. In particular, a first data set having known geologic characteristics is compared, via the cross-correlation technique, with a second data set having unknown geologic characteristics. As a result of this comparison using the cross-correlation technique, an output record, known as a xe2x80x98correlation spectral volumexe2x80x99, is generated. The xe2x80x98correlation spectral volumexe2x80x99 records and displays the degree to which the unknown geologic characteristics of the second data set substantially matches one or more of the known geologic characteristics of the first data set. The first data set does not include one or more traces from an input seismic volume. Rather, the first data set can include any suitable set of traces that one would want to use as xe2x80x98standard comparison traces having known geologic characteristicsxe2x80x99. In particular, in the embodiments of invention disclosed herein, the first data set (which represents the xe2x80x98standard comparison traces having known geologic characteristicsxe2x80x99) is comprised of two or more traces having known geologic features and includes either a set of Kernel Functions or a Synthetic Model derived from a Geologic Model. The second data set having unknown geologic characteristics include either a plurality of autocorrelation functions which are derived from a corresponding plurality of input seismic volume traces or the plurality of input seismic volume traces.
Further scope of applicability of the present invention will become apparent from the detailed description presented hereinafter. It should be understood, however, that the detailed description and the specific examples, while representing a preferred embodiment of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become obvious to one skilled in the art from a reading of the following detailed description.